1. Field of the Invention
This invention relates in general to the field of rotating toys. More specifically it relates to the yo-yo.
2. Description of Prior Art
The term yo-yo was derived from the equivalent meaning of come-come in the native language of the Philippines where the toy is thought to have evolved from an ancient weapon. Stones with a groove around the periphery have been found in archaeological sites. It is believed that the groove was carved in order to secure a twine or strip of leather to the stone. A warrior or hunter could thus throw the stone, quickly recover it and throw it again. Archaeologists have shown that over many years the groove had been made deeper, presumedly at first to allow the twine to be all wound within the groove for the convenience of carrying it. The user would not have thrown the stone from the wound-up condition to wound an animal or an enemy because this would have resulted in primarily rotational speed of the stone instead of linear speed. The first to have carved a deep groove would have allowed the stone to drop while holding the end of the twine only for the purpose of letting the string out. When the stone reached the end of twine and rotated back up the string the come-come was discovered.
In the 1920s a Phillipino named Pedro Flores invented the sleeping yo-yo. Instead of tying the string to the axle, he looped the string around the axle to allow the yo-yo to spin freely in the loop at the end of the string without returning up to the user's hand. This free spinning is referred to as sleeping. The sleep condition is used to perform many trick maneuvers. The yo-yo may be returned to the users hand from the sleep condition by a slight jerk of the string. The phenomenon that takes place here is that: Following the jerk, the string becomes slack for a moment and allows the semi-tight loop to wind up on the axle, increasing the frictional drag as more string is wound around the axle and becomes wedged in the gap between the inertial masses.
There have been numerous efforts to improve yo-yo performance. A novelty search of prior art relating to the yo-yo discovered the following patents:
______________________________________ U.S. Pat. No. Classification Inventor ______________________________________ 1,419,402 6/1922 446/250 Mosher 2,591,954 4/1952 446/250 Madsen 2,629,202 3/1953 446/250 Stivers et. al. 2,645,881 7/1953 446/250 Frangos 2,676,432 4/1954 446/250 Field 2,773,328 12/1956 446/250 Fraenkel et. al. 2,891,351 6/1959 446/250 Madaras et. al. 2,975,547 3/1961 446/250 Greve 3,081,578 3/1963 446/250 Mosher 3,175,326 3/1965 446/250 Isaacson 3,184,885 5/1965 446/250 Gibson 3,256,635 6/1966 446/250 Radovan 3,444,644 5/1969 446/251 Sayegh 3,805,443 4/1974 446/250 Duncan 4,130,962 12/1978 446/250 EnnIs 4,207,701 6/1980 446/250 Kuhn 4,290,225 9/1981 446/250 MacCarthy 4,318,243 3/1982 446/250 MacCarthy 4,332,102 6/1982 446/250 Caffrey 4,437,261 3/1984 446/250 MacCarthy 4,442,625 4/1984 446/250 MacCarthy 4,895,547 1/1990 446/250 Amaral 5,017,172 5/1991 446/250 Seifert 5,100,361 3/1992 446/250 Kuhn Foreign Patents 22,401 10/1903 England 446/251 Weisshappel 15,824 4/1904 Austria 446/251 Weisshappel 209,288 1/1924 Philippine 446/250 Murray Islands 504,033 4/1936 England 446/266 Beresford ______________________________________
A close approach to the disclosed construction and function of the present invention was not observed in the above cited patents. Perhaps of most merit are patents: U.S. Pat. No. 2,891,351 to Madaras et. al. claims "--bodies in adjustably connected spaced relation for receiving a spirally wound string--". The hub bosses in this invention, appearing similar in construction, have no functional relationship to the lapper disks of the present invention. The hub boss are in contact with each other as stated: "--to maintain the confronting bodies in minimum spaced relation--". The string in this invention stays outside the perimeter of the hub bosses in this invention. The trunions extending outward on this invention "--define knurled cylindrical end portions providing convenient finger gripping surfaces to impart a manual or hand spinning twist--" such that each of the two body halves may be used separately as spinning tops. These knurled trunions are not functionally equivalent to the knobs of the present invention. The knobs in the present invention are separate from the inertial disk and hubs. U.S. Pat. No. 3,256,635 to Radovan claiming radial flutes that grip the string. U.S. Pat. No. 4,130,962 to Ennis claiming cone shaped protuberances to aid the gripping of the string. U.S. Pat. No. 2,629,202 to Stivers et. al. claiming vanes on the axle surface adjacent to the central polished zone and friction disks with an adhesive characteristic ridgedly mounted on the axle to aid the binding of the string in the gap. These devices do not relate to the initiation of string wind-up. These devices make contact with the string only after the string has made several wraps around the axle and has spread out laterally. This is stated so by Stivers where he refers to the string "--shifted into contact therewith--" and "--expansion of the loop incident to relaxed tension upon the string." These devices cause the string to fray and shorten string life. The present invention utilizes smooth lapper disks where the gap between them is adjustable to make a skimming contact with the cord. U.S. Pat. No. 3,175,326 to Isaacson claims a ball bearing to reduce friction between the string and the shaft to attain longer sleep times. In order to return the yo-yo to the hand, strands of the string must become caught in the circumferential gap between the periphery of the bearing and the rotating body. U.S. Pat. No. 4,332,102 to Caffrey claiming use of a bearing and a centripitally activated clutch to return the yo-yo to the hand. This invention demonstrates the difficulty of making a yo-yo with very low running friction and having the yo-yo reliably return to the hand at will. U.S. Pat. No. 4,207,701 to Kuhn utilizes a threaded shaft to allow disassembly for easy replacement of the wooden axle which is subject to wear. The two body halves are rotated relative to each other to secure the wood axle within the inward facing counterbores. There is no adjustment feature in this invention. U.S. Pat. No. 4,895,547 to Ameral utilizes a low friction spool on a metal axle having threaded ends. A shoulder at the juncture of the unthreaded portion of the axle interfaces with the face of the threaded insert in each of the yo-yo halves. This interface and associated tolerances allow the yo-yo halves to be tightened on the axle and establishes the space for free rotation of the spool on the axle. This yo-yo has no friction adjustment feature. U.S. Pat. No. 5,017,172 to Serfert utilizes a threaded axle and yo-yo hubs having threaded inserts equivalent to Ameral's invention also incorporating convertible spinning top functions. This invention has no tether gap adjustment features. U.S. Pat. No. 5,100,361 to Kuhn et. al. utilizes a threaded axle as a means of adjusting the gap between the "disk like sides". This invention represents another step in the evolution of low friction sleeping yo-yos. It is dependent on the lateral expansion of an unloaded elastic tether to engage the "disk like sides" to initiate the wind up of the tether from the sleep condition. The adjustment feature requires dismantling of the body halves. A tool or finger nail is required to counter torque the threads to seize the body halves on the axle. Kuhn is staying with the tradition of having the yo-yo body halves fixed to the axle. This is the closest approach to the present invention. The differences between Kuhn's invention and the present invention are as follows:
Kuhn et. al. utilize a smooth disk with a radial dimension equivalent to one tether strand diameter. The tether is looped around the outer bearing race twice such that the greatest width of the tether is at and below the center of rotation where the elastic expansion occurs and makes contact with the disk like surfaces. It is interpreted that the change in friction for initiation of tether windup is caused by the longitudinal elasticity of the tether strands whereby the strands expand diametrically as the strands contract longitudinally during the slackened tether condition. This interpretation requires truly an elastic tether as claimed, not simply a flexible tether.
The present invention utilizes a yoke with an aperture for connecting a single cord tether. The cord is straight with a circular cross section during the sleep condition. The lapper disks have a radial dimension of multi-tether diameters. The lapper disks are in skimming contact with the tether extending above the yoke during the sleep condition. The slackened tether is lapped up in multi-loops between the disks. The frictional drag during the windup of the slackened tether is amplified by the increase of linear tether contact and the transition from tether circular to oval cross-section induced by loop curvature. There is no need to dismantle the present invention to adjust the gap between the two inertial disks. The inertial disks of the present invention are independently rotatably and slidably mounted on the axle. The maximum gap is limited by a threaded knob on the end of the axle having residual torque to fix the adjustment. There is no need for an elastic tether in the present invention.
In all the prior art discovered the yo-yo halves are fixed to the axle or seized to the axle during operation and spin as a unit. All known prior art sleeping yo-yos use a tether consisting of strands looped over the axle or over a bearing or spool resulting in twisted strands and thereby causing a residual torque inducing dreaded precession. All known prior art sleeping yo-yos are designed to have the tether free of any pressureful contact with the inside surfaces of the yo-yo halves during the sleep condition. The present invention utilizes a slight skimming contact between the tether and the lapper disks. The initialization of tether windup is caused by this slight skimming friction, friction between the axle and yoke and circular air motion in the gap between the two inertial disks whereby an arch is formed in the slackened tether whereby the tether cross section becomes oval whereby frictional drag is increased.
The following improvements to yo-yo construction have been patented: U.S. Pat. No. 2,975,547 to Greve claims the two inertial masses mounted on a split pin, allowing the yo-yo to be assembled in different configurations. U.S. Pat. No. 3,081,578 to Mosher uses a hollow sleeve rotatably journaled on a shaft. The shaft is terminated on each end with an abutment. The abutment is used as part of a means of attachment to a finger to allow the user to grip the shaft with one hand while the string is pulled with the other hand to spin the disks. The two inertial disks of this invention are fixed on the sleeve. The floating shaft of this invention is not functionally nor constructurally similar to the present invention. Mosher's invention also has bands of resilient material disposed around the outer maximum periphery of each of the disks for providing a cushioning effect to the disk. The purpose of the resilient material as stated is to cushion the disks--that is to protect the disk. The slight thickness and width of the resilient material is not an effective cushion for the hand. The design of the present invention allows sufficient thickness and width of resilient material to give the feel of catching a rubber ball as the yo-yo returns up the tether to the hand. U.S. Pat. No. 3,805,443 to Duncan Jr. claims the use of a rivet to rigidly clamp the inertial masses to a spool. There are no constructional nor functional equivalences between these inventions and the present invention. U.S. Pat. No. 2,676,432 to Field claims an annular collar with a gap for fixing the string with a knot or flattened end. This is not a sleeping yo-yo. The collar is part of the rotating inertial masses and therefore is not equivalent to the yoke of the present invention.
Foreign patents to Weisshappel, 22,401 in England and 15,824 in Austria claims a "cord fastened by one end" in the base of a deep groove. This is not a sleeping yo-yo and thus has no functional relationship to the present invention. 504,033 to Beresford in England claims an "eye member" to form a loop for use in rope games. This "eye member" is similar to the hitch member claimed as part of the present invention. Beresford does not describe how the cord end is secured in the blind hole of the "eye member". The hitch member of the present invention has a conical shaped through aperture for capturing the bulbous end of the tether cord. There is no known prior art of yo-yo tethers having a hitch as described in the present invention.
The present invention also discloses the use of a Velcro latching strap to attach the end of the tether opposite axle end to the operators finger. This use was not found in prior art.
The present invention also utilizes the existing state of the art yo-yo tether--a string looped once over the axle and twisted to form a coiled single strand. This tether was patented by Murray of the Philippine Islands in 1924. This tether is employed as part of every sleeping yo-yo found in prior art patents. Adjustable performance and non-adjustable yo-yos utilizing lapper disk with this tether are disclosed.